Improvement in tunnels



i @einen tatra @anni @fitta IMPROVEMENT IN TUNNELS.

dite .straalt aferra tu in tipa rtter patent mit making mit 'nf tige une.

TO ALL WIIOM IT MAY CONCERN:

Be it known that I, JGSEPH DIXON, of the city, county, and State of New York, have invented a new and useful Mode of Constructing Cast-Iron Tunnels for underground railroads; and I do hereby declare that the following is a full, clear, and exact descriptionvthercof, whichwill enable others skilled inthe art to makeand use the same, reference being had 't'o the accompanying drawings, forming part of this specification, in which- Figure 1 is an end elevation of my improved mode of constructing tunnels for underground railroads, die.

Figure 2 is a side elevation of the same. y

Figure 3 is a plan view ofl the same.

` Similar letters denote like parts. i i

-The nature of this invention consists in an improved mode of constructing tunnels for underground railroads, sewers, vaults, Src., of any required size, by means of a series of cast-iron plates or. slabs, as shown in "the accompanying drawingaround each of whose edges-ds a vstrong rim or iiange,by which these plates are securely bolted4 together, as more fully described'hereinafter, the sides resting in a groove on a foundation of masonry. i I

In figs.V l and 2, A A represent the side plates or slabs of the tunnel, *which may restjon--anysuitably preparedfoundation. The plates or-slabs A A are cast with Va strong rim or ilange,-C, .aroundieech of them, and are tongued and grooved, as shown in parts broken away in gs. 2 an'd 3. B etween allv the 'joints I place a strip of rubber, felt, or other pliable substance in order to secure aperfectly tightjoint when the bolts and nuts are screwed `up tight. The roof-plates D ofthe tunnel are c astin curves or pai-.ts of a circle, soas to forml an arch of the required radius to span the tunnel, the centrerp'late acting as the key of thc circle.

' In order to construct a tunnel according to my plan, some of the plates orV slabs A are set up edgewise on the foundation, and their endsbolted together. jI then place another series of plates or slabs A on top of each of the plates before'set, andbolt the lower danges thereof to the flanges of the plates beforeset, and I thus complete the sides of the tunnel. I A movable frame, arched on the top like the tunnel, is then wheeled between the sides, and the arch plates or slabsplaced on-the top ofthe framework, one by one, .and theirfianges bolted together. This framework being made so as to be raised or loweited as may be required by means ofa screwjack, will be raised slightly above the sides while the flanges of the arch-plates are' being bolted together, and when the arch is ready the framework is to be lowered till the arch rests in its place on the sides A. The arch and sides are now to be bolted securely together, and the framework wheeled out; the arch is then complete, the centre plate acting as the key, and the anges of every joint acting asa-powerful strengthening rib onthe outside. Theijoints inside the tunnel thus formedwill be iushwith eachf other, and will have theappearance of beingcast in one piece likea cylinder, so that nothing can lodge inA the same chosen to be used as a sewer, water pipe, or culvert. I breakl joint in the centre ofeach plate orf's'lab, as shown in figs. 2 and 3.. By thus varying the line of jouting I gain great additional strength'to the Whole structure. The means of ventilation` will be through iron air-shafts from the tunnel to the surface of the street, rising in the form of an Obelisk or column of open lattice-work. p i i By the means herein described a tunnel of unlimited dimensions can be madel with great rapidity, and at a much less cost than mason-work. A tunnel constructed according to my plan, with iron Vplates one-half inch thick, and with rims or flanges three inches deep, would answer for eighteen inches of masonry, and consequentlysave a large amount of excavating; also the labor of hauling lime, sand,&c.', and of lthe mixing of the same. The plates would bebrought to the place of use with holes drilled for the bolts, and could be set up by ordinary unskilled laborers under the direction of an Overseer.`

I am aware that it has been` proposed to make tunnels by the longitudinal bolting together ofshort tubes,`

but this I dolnotclaim. It'lias been the study of engineers`for a long time to find some simple, cheap, and water-tight arrangement for the purpose of constructing a tunnel for underground roads, andalso for large sewer and water pipes. The diiiiculty of casting a cylinder of large dimensions is well known to all experienced engineers, owing tothe thinness of metal required for such purposes, which is apt to chill` in the moulds and produce flaws, even under the most favorable circumstances. By the use of my improvement I form the tunnels .fof separate plates, cast in such amanner and of such size and form that they'can be easily handled, while good sound castings can always be insured at a low cost. By my mode of constructing tunnels, I can also construct sewers or waterpipes very cheaply, 'of any desired form or any required diameter.

l claim as new, and desire t'o secure .by Letters Patent-l- A subterranean or submarine tunnel, the walls and roof of which are constructed of rectangular metallic plates, each one of which has a. lip or flange tur-ned up around its -four edges,tl1'e plates being bolted together through the iianges, arranged so as-to break joints, and packed tightly at the seams, substantially in the manner and for the purpose specified.

JOSEPH DIXON.

Witnesses:

WM. F. McNAMARA, ALEX. F. RoBERTs. 

